1. Field of the Invention
The present invention relates to a multilayer ceramic capacitor and a circuit board with a multilayer ceramic capacitor mounted thereon.
2. Description of the Related Art
A multilayer ceramic capacitor, a laminated chip electronic component, is a chip-type condenser installed on a printed circuit board (PCB) of various electronic products such as imaging devices (or video apparatuses) like liquid crystal displays (LCDs), plasma display panels (PDPs), and the like, computers, smart phones, portable phones, and the like, to charge and discharge electricity.
A multilayer ceramic capacitor (MLCC), having advantages such as compactness, guaranteed high capacity, and ease of mountability, may be used as a component of various electronic devices.
The MLCC may include a plurality of dielectric layers and internal electrode, having a structure in which internal electrodes having different polarities are alternately laminated between the dielectric layers.
The dielectric layers have piezoelectric and electrostrictive properties. Thus, when a DC or AC voltage is applied to an MLCC, a piezoelectric phenomenon occurs between internal electrodes, generating vibrations.
Vibrations are transferred to a PCB on which the MLCC is mounted, through solders of the MLCC, inducing the entirety of the PCB to become an acoustically radiating surface to generate vibratory sound as noise.
Vibratory sound may correspond to audio frequencies ranging from 20 Hz to 2000 Hz, making users uncomfortable, and such vibrating sound which may cause discomfort to users is known as acoustic noise.
In order to reduce acoustic noise, a product in which a lower cover layer of an MLCC is increased has been studied.
Also, an MLCC having an increased lower cover layer is mounted as a horizontal mounting type MLCC such that a relatively thick lower cover layer is positioned on the bottom on a printed circuit board (PCB) to advantageously reduce acoustic noise.
Meanwhile, in the case of a product in which a thickness of a lower cover layer of an MLCC is increased in order to reduce acoustic noise, an amount of laminations is increased or dielectric layers are thinned in order to implement high capacitance, causing a delamination defect or a degradation of breakdown voltage (BDV).